String theory in the infrared

TL;DR

This paper explores the low-energy phases of string theory using a global perspective, revealing universal IR scaling relations and holographic bounds that support swampland conjectures and potential cosmological signatures.

Contribution

It introduces a worldsheet analysis connecting UV/IR relations in string theory to holographic bounds, advancing understanding of the landscape and swampland.

Findings

Higher-derivative Wilson coefficients exhibit UV/IR relations.

Vacuum energy satisfies holographic bounds.

Infrared data of string theories are connected by universal scaling relations.

Abstract

I briefly summarize a recent research program aiming to probe the landscape of low-energy phases of string theory from a global perspective. Borrowing conceptual lessons from the swampland program, I will discuss how the effective theories of gravity produced by low-energy string theory are far from generic; rather, their infrared data is connected by universal scaling relations which become non-trivial in species limits. In particular, a worldsheet analysis reveals that higher-derivative Wilson coefficients and the vacuum energy exhibit UV/IR relations which are invisible from the viewpoint of effective field theory, leading to parametric inequalities which take the form of holographic bounds. This lends a more solid theoretical support to swampland-motivated phenomenological scenarios, and to the broader hopes of extracting less direct, but empirically accessible, signatures of string theory from cosmological observations.